Digital Systems Design Course: COE 424 Lebanese American University Homework #3 Spring 2015 Problem 1: While respecting the order implied by the parentheses, implement the following function in VHDL. g = (A - (B + C)) - (D - ((E + F) - G)) a. b. Implement a behavioral design Implement a structural design after implementing behavioral descriptions of the adder and subtractor (no resource constraints). c. Implement a structural design if one adder is available (unlimited subtractors), after implementing behavioral descriptions of multiplexers and registers. d. Implement a structural design if one adder and one subtractor are available. For all structural cases above, assume 2-input arithmetic components only with 20 ms delay for adders, 25 ms delay for subtractors, 10 ms delay for registers, and 15 ms delay for multiplexers – irrespective of the size of registers and multiplexers. With the exception of the presence or absence of control signals, all designs must have the same entity declaration in VHDL. Any select and enable signals can be provided externally; no need to generate them internally. Submit your paper designs. Problem 2: Design a VHDL testbench in order to test all four architecture implementations given in Problem #1 above. In the testbench, you should have a process which changes the input vector in the following way: each input (A, B, C, D, E, F, G) can take one of two different values: 2 or 5; thus, the input vectors should be: (2, 2, 2, 2, 2, 2, 2), (2, 2, 2, 2, 2, 2, 5), (2, 2, 2, 2, 2, 5, 2), (2, 2, 2, 2, 2, 5, 5), … (5, 5, 5, 5, 5, 5, 5). Problem 3: Control generation: a. Design a behavioral VHDL design of an automated controller producing the control signals of Problem #1 part (d). b. Design a structural paper design (no VHDL required!) of an automated controller producing the control signals of Problem #1 part (d). Note: The assignment is to be typed and submitted at class-time. Note that: 1. Hand-written assignments will NOT be accepted. 2. Assignments submitted by email will NOT be accepted. 3. Late assignments will NOT be accepted. 4. Figures can be drawn by hand. Leave the right amount of space in your typed document to draw your figures. 5. Common work and/or cheating are NOT accepted. All parties involved will receive a zero that will NOT be dropped when computing the grades at the end of the semester. Due Date: Tuesday April 7, 2015.